Instrumented spindles and load cells are used to measure a number of things, including, for example, the forces and moments on a tire. In most cases, there is a tradeoff between high load and high resolution. It is difficult to measure a high load with high resolution.
Load cells typically utilize an engineered compliance to operate. For example, a typical method is to build a device that is strong enough to hold a given load range, but has an engineered compliance range that can be measured, often in the form of a displacement or a strain given the load applied. This is how a fish scale works—there is a spring that provides a compliance (i.e. stretch) that is proportional to the load applied. The resulting displacement of the hook due to the stretch of the spring is measured by a dial or indicator. A calibration factor is applied to correlate the position of the dial or indicator to a particular load. Higher loads often require stiffer measuring instruments, but stiffer measuring instruments make it difficult to attain higher resolutions due to limitations in instrumentation. For example, to measure a whale, the fish scale would need to have an extremely stiff spring, otherwise it would fail under the load. If one tries to use the same fish scale to weigh a goldfish, the very stiff spring would not deform enough to be measured by the dial or indicator using the naked eye. Thus, the problem of high load versus high resolution.
Thus, what is still needed in the art is an instrumented spindle or load cell that is capable of measuring a range of loads, including high loads, with high resolution, while avoiding the need to utilize expensive instrumentation.